1. Field
Exemplary embodiments of the present invention relate to a memory that may prevent degradation of stored data due to word line disturbance in a memory cell and a memory system including the same.
2. Description of the Related Art
As the degree of integration of a memory increases, an interval between a plurality of word lines included in the memory is reduced. As the interval between the word lines is reduced, a coupling effect between adjacent word lines increases.
Whenever data is inputted and outputted to and from a memory cell, a word line toggles between an activated or active state and a deactivated or inactive state. As the coupling effect between adjacent word lines increases as described above, data of a memory cell connected with a word line adjacent to a frequently activated word line is damaged. This is known as word line disturbance. Due to the word line disturbance, a problem arises wherein the data of a memory cell may be damaged before the memory cell is refreshed.
FIG. 1 is a diagram illustrating a part of a cell array included in a memory.
In FIG. 1, ‘WLL’ indicates a word line that has a large number of activations or a high activation frequency and ‘WLL−1’ and ‘WLL+1’ indicate word lines that are disposed adjacent to the word line ‘WLL’. ‘CL’ indicates a memory cell connected with the word line ‘WLL’, ‘CL−1’ indicates a memory cell connected with the word line ‘WLL−1’ and ‘CL+1’ indicates a memory cell connected with the word line ‘WLL+1’. The respective memory cells ‘CL’, ‘CL−1’ and ‘CL+1’ include cell transistors TL, TL−1 and TL+1 and cell capacitors CAPL, CAPL−1 and CAPL+1.
In FIG. 1, when the word line ‘WLL’ is activated or deactivated, the voltages of the word lines ‘WLL−1’ and ‘WLL+1’ are increased or decreased due to a coupling effect occurring among the word lines ‘WLL’, ‘WLL−1’ and ‘WLL+1’ and an influence is exerted on the amounts of charges of the cell capacitors CAPL−1 and CAPL+1. Therefore, frequent activation of the word line ‘WLL’ results in the word line ‘WLL’ toggling between an activated state and a deactivated state and leads to increased changes in the amounts of charges stored in the cell capacitors CAPL−1 and CAPL+1 included in the memory cells ‘CL−1’ and the ‘CL+1’, so that the data of the memory cells ‘CL−1.’ and the ‘CL+1’ may be degraded.
Furthermore, as electromagnetic waves, which are generated while the word line toggles between the activated state and the deactivated state, introduce or discharge electrons into or from the cell capacitors of the memory cells connected with adjacent word lines, data may be damaged.